Optical fiber for light amplification

Abstract

A fiber, with enhanced stimulated Raman scattering for use in light amplification, transmits light wave energy in a single mode. The fiber includes a cylindrical core of light transmitting material doped with a substantial concentration of GeO 2 , an inner cladding of light transmitting material doped with a sizable concentration of GeO 2 (but less than the substantial concentration) surrounding the core, and an outer cladding of GeO 2 -free material surrounding the inner cladding.

What is claimed is: 
     
       1. An optical fiber for transmitting light wave energy in a single mode comprising: a cylindrical core of a first light transmitting material, doped with a substantial concentration of GeO 2  at x mol percent;   an inner cladding of a second light transmitting material, doped with a sizable concentration of GeO 2  at y mol percent, surrounding said core; and   an outer cladding of material, substantially free of GeO 2 , surrounding said inner cladding.   wherein x is greater than y; and   wherein a GeO 2  -enhanced Raman effect is produced.   
     
     
       2. The optical fiber as recited in claim 1 wherein y is at least 15. 
     
     
       3. The optical fiber as recited in claim 2 wherein x=20 and y=15. 
     
     
       4. The optical fiber as recited in claim 2 whereby enhanced light amplification by stimulated Raman scattering is produced. 
     
     
       5. The optical fiber as recited in claim 1 wherein said inner cladding is contiguous to said outer cladding, and wherein a portion of said inner cladding contiguous to said outer cladding contains a transitional portion of GeO 2 , tapering from y mol percent to zero mol percent. 
     
     
       6. In combination, an optical fiber comprising: a silica core doped with substantial concentration of GeO 2  ;   an inner silica cladding doped with a sizable concentration of GeO 2 , but less than said substantial concentration; and   an outer silica cladding contiguous with said inner cladding; and   wherein a GeO 2  -enhanced Raman effect is produced.